Compressor control valve

ABSTRACT

1,043,806. Valves. BENDIX-WESTING- HOUSE AUTOMOTIVE AIR BRAKE CO. March 20, 1964 [March 26, 1963], No. 11963/64. Heading F2V. [Also in Division G3] A valve suitable for insertion in the line between a compressor and a receiver comprises an inlet chamber 12, a delivery chamber 14 and a check valve 60 allowing flow from the inlet to the delivery chamber. The check valve forms part of a piston 46 slidable in bore 47 and co-operating with a stop 48 carried by a spindle 42. The latter also carries an exhaust valve 36 loaded by a spring 54. When the pressure in the inlet chamber reaches a predetermined value it unseats the exhaust valve with a snap-action and the lowered pressure in the inlet chamber then allows the piston 60 to be driven downwardly by the receiver pressure until it engages stop 48, whereby the exhaust valve is retained open until the receiver pressure drops to a second, lower, predetermined value. In modifications, the piston and exhaust valve are rigidly interconnected, or the spindle 42 is rigid with the piston and the exhaust valve is slidable on the spindle with its loading spring in exhaust chamber 35. A filter may be provided in the inlet chamber upstream of the check valve. The latter comprises an annular gasket supported on a plate 64 retained by a snap-ring 66.

July 4, 1967 MORSE ETAL 3,329,154

COMPRESSOR CONTROL VALVE Filed March 26, 1963 INVENTOR ROBERT 'J. MORSEHARRY M. VALENTINE ATTQRNEYS United States PatcntOfiFicc 3,329,154Patented July 4, 1967 3,329,154 COMPRESSOR CONTROL VALVE Robert J. Morseand Harry M. Valentine, Elyria, Ohio, assignors to Bendix-WestinghouseAutomotive Air Brake Company, Cleveland, Ohio, a corporation of DelawareFiled Mar. 26, 1963, Ser. No. 267,986 2 Claims. (Cl. 137-116) Thisinvention relates to fluid pressure responsive valves and moreparticularly to a valve for automatically controlling the delivery ordischarge side of an air compressor.

The object of the present invention is to provide a novel valveresponsive to the delivery pressure of an air compressor and adapted tobe interposed between the delivery side of an air compressor and a fluidpressure receiver or reservoir to serve the combined functions of agovernor, discharge line unloader, check valve, drain valve and safetyvalve.

The invention is hereinafter described in detail in conjunction with thesingle, partly schematic drawing which includes a vertical crosssectional view of a valve embodying the features of the invention.

Referring now to the drawing, the valve of the invention comprising acasing having inlet and delivery cavities 12, 14 provided with inlet anddelivery ports 16, 18 respectively connected to the discharge line 20 ofa compressor 22 and to a delivery line 24 connected to a fluid reservoir26.

The casing 10 is composed of an upper part 28 and a lower part 30 whichis threadingly connected to the upper part as shown and includes anannular shoulder 32 surrounding an exhaust port 34 leading into anatmospheric cavity 35 and normally closed by a spherical valve member 36which sealingly engages a conical valve seat 38 on the outer ordownstream side of the exhaust port 34. The valve 36 is provided with acentral bore 40 receiving the lower threaded end of a plunger 42 whichextends upwardly through the inlet cavity 12 and is slidingly receivedat its upper end in a bore 44 drilled in the lower end of a piston likemember 46 slidingly received in an upper reduced diameter part 47 incasing member 28 and hereinafter described in detail. The plunger 42carries adjacent its upper end an abutment member 48, which may be a nutas shown or other suitable collar, having upper and lower surfaces 50,52. Interposed below the lower surface 52 of the abutment 48 and theshoulder 32, surrounding the exhaust opening 34, is a regulating spring54 which serves to urge the valve 36 at all times to its closedposition.

Referring now to the piston member 46, this may be of elongated,cylindrical construction having a lower end 56 adapted to engage theupper surface 50 of the abutment 48 when the member 46 is moveddownwardly in a manner which will become apparent. The member 46 may beprovided with an integral annular collar 58 whose lower surface providesthe upper support for the flat inner part of a cup gasket 60 having asealing flange 62 extending in the direction of the delivery cavity 14.The lower side of the gasket 60' is supported by an annular ring 64retained in place by a snap ring 66 received in a groove about themember 46 as shown. The cup gasket 60 is constructed and arranged as acheck valve to permit fluid under pressure to flow past the periphery ofthe sealing flange 62 from the inlet 12 to the delivery 14 cavities butprevents fluid flow in the reverse direction.

In operation, assuming that there is initially no pressure in thereservoir 26 when the compressor 22 is operated fluid flows by way ofthe discharge line 20 through the inlet port 16 into the inlet cavity 12and thence past the sealing flange 62 into the inlet cavity 14 and fromthere to the reservoir 26 by way of port 18 and conduit 24. As thecompressor continues to operate, pressure builds up throughout theentire system and acts downwardly on the exhaust valve 36 through theexhaust port 34. The effective area of the exhaust valve is a functionof the diameter of the exhaust port and when system pressure acting onthis elfective area exceeds the upward or closing force of the spring54, the valve 36 is forced off the seat 38 thereby exposing the entirecross sectional area of the valve to system pressure so that it isdriven to its fully open position with a snap action. Upon thisoccurrence, all of the pressure existing in the inlet cavity 12 isexhausted to atmosphere with the result that the pressure in thereservoir 26 acts in a reverse direction through the conduit 24 anddelivery port 18 onto the upper side of the cup gasket 62 to spread thesealing flange into sealing engagement with the side wall of thedelivery cavity 14 and at the same time exerts a down- Ward force on thecylinder member 46 which at this stage is unopposed by pressure in theinlet cavity 12, this being now substantially at atmospheric pressuredue to the open condition of the valve 36-. The piston member 46descends until the lower edge 56 of the piston member engages the uppersurface 50 of the abutment 48 thus preventing the valve member 36 frombeing returned by the spring 54 to its closed position so long as thedownward pressure force acting on the upper surface of the piston memberand cup gasket exceeds the upward force of the spring 54.

With the valve 36 in its fully open position and retained in thisposition by the above described action of the piston member 46, it willbe apparent that thecompressor is effectively unloaded and delivers itsentire output directly to atmosphere through the open exhaust port 34.It should also be apparent that any liquid which might have accumulatedin the discharge line 20 or in the inlet cavity 12 is also discharged toatmosphere through the exhaust port 34.

Assume now that the pressure in the reservoir 26 starts to fall andcontinues to fall until it reaches a level Where the downward forceacting on the piston member 46 is less than the upward force of thespring 54 acting on the piston 46 through the abutment member 48. Atthis stage the parts of the valve commence moving toward their upperposition of the drawing and continue to move in this direction until thevalve 36 engages the conical seat 38 thereby closing the exhaust port.Immediately upon this occurrence pressure builds up in the inlet cavity12 and acts on the underside of the piston member 46 to drive this toits fully raised position of the drawing with a snap action. Thereafterfluid flows past the periphery of the gasket 60 to the reservoir 26 aspreviously described until the pressure in the system again rises to alevel suflicient to unseat the exhaust valve 36 where upon the abovedescribed cycle of operation is repeated.

A particularly desirable feature of the valve of the present inventionis that the exhaust valve is movable between its open and closedpositions independently of the piston 46, such independent movementbeing afforded by the sliding of the piston bore 44 with respect to theupper end of the plunger 42. With this arrangement, it should beapparent that should the piston member, for whatever reason, stick tothe casing, the valve 36 will nevertheless move to its open positionwhen the system pressure reaches a predetermined high value establishedby the spring 54 and thus serves as a safety valve to prevent the buildup of system pressure above a safe level.

Not only does the valve of the invention operate as an unloader and aliquid discharge valve, as well as a check and safety valve, but byselective correlation of the eifective motive areas, the valve serves asan efficient compressor governor; that is to say, with proper selectionof motive areas the pressure at which the valve opens may besignificantly different from the pressure at which the valve closes, Forexample, in order for the valve to remain open until reservoir pressurehas fallen to a level substantially below the pressure at which thevalve was opened the effective cross sectional area defined by thediameter of the cup gasket or the reduced diameter part 47 is madelarger than the diameter of the exhaust port 34. It will thus beapparent, that a high pressure acting on the effective area of theexhaust valve sufficient to compress the spring 54, and open the valve36, will be balanced by a lower reservoir pressure acting across thegreater effective area on the upper side of the cup gasket and pistonmember 46. An additional factor insuring a lower closing pressure is thefriction force between the lip or flange 62 of the cup gasket 60 and thewall of the upper part 47 of the casing after the lip 62 has been movedinto sealing engagement with the wall by reservoir pressure upon openingof the exhaust valve.

It will be apparent to those skilled in the art that the embodiment ofthe invention shown and described is illustrative only. For example,though it is desirable that there be independent or lost motioncooperation between the piston member 46 and the exhaust valve 36 inorder that the exhaust valve can serve additionally as a safety valve asexplained above, this arrangement is not essential inasmuch as the valvewill operate effectively if the piston and exhaust valve are rigidlyinterconnected, and in certain environments this arrangement might bepreferable. Other modifications are: an arrangement where the plunger 42is rigid with the piston 46 and the exhaust valve is slidable withrespect to the plunger; the location of the spring 54 in the atmosphericcavity 35; and the inclusion of a filter in the valve casing between theinlet port 16 and the cup gasket 60. The foregoing modifications and avariety of others may be resorted to without, however, departing fromthe scope and spirit of the appended claims.

What is claimed is:

1. A fluid pressure control valve comprising a casing,

a fluid pressure responsive element dividing the interior of said casinginto separate inlet and delivery cavities, inlet and delivery portsrespectively connected to said cavities, an exhaust port connected tosaid inlet cavity, a check valve carried by said pressure responsiveelement for permitting the one-way How of fluid from said inlet to saiddelivery cavity but not in the reverse direction, said check valveforming a part of said pressure responsive element and slidably engagingthe interior wall of said casing, an exhaust valve for controlling saidexhaust port and having an effective area responsive to the pressure insaid inlet cavity for moving said valve to its open positionindependently of said element, resilient means urging said exhaust valveat all time towards its closed position, and plunger means including alost motion connection interconnecting said exhaust valve and said fluidpressure responsive element to retain said exhaust valve open only aftermovement thereof to its open position in response to pressure in theinlet cavity and upon movement of the pressure responsive elementtowards said exhaust valve to take up said lost motion connection, inresponse to pressure trapped in the delivery cavity by closing of saidcheck valve upon opening of said exhaust valve.

2. The control valve of claim 1 wherein the efiective area of saidexhaust valve is less than the efiective areas of said pressureresponsive element exposed respectively to said inlet and deliverycavities.

References Cited UNITED STATES PATENTS 2,395,941 3/1946 Rockwell l37l15X 2,855,944 10/1958 Albin 137l02 2,952,267 9/1960 Reis 137l15 WILLIAM F.ODEA, Primary Examiner.

ISADOR WEIL, Examiner.

D. H. LAMBERT, Assistant Examiner.

1. A FLUID PRESSURE CONTROL VALVE COMPRISING A CASING, A FLUID PRESSURERESPONSIVE ELEMENT DIVIDING THE INTERIOR OF SAID CASING INTO SEPARATEINLET AND DELIVERY CAVITIES, INLET AND DELIVERY PORTS RESPECTIVELYCONNECTED TO SAID CAVITIES, AN EXHAUST PORT CONNECTED TO SAID INLETCAVITY, A CHECK VALVE CARRIED BY SAID PRESSURE RESPONSIVE ELEMENT FORPERMITTING THE ONE-WAY FLOW OF FLUID FROM SAID INLET TO SAID DELIVERYCAVITY BUT NOT IN THE REVERSE DIRECTION, SAID CHECK VALVE FORMING A PARTOF SAID PRESSURE RESPONSIVE ELEMENT AND SLIDABLY ENGAGING THE INTERIORWALL OF SAID CASING, AN EXHAUST VALVE FOR CONTROLLING SAID EXHAUST PORTAND HAVING AN EFFECTIVE AREA RESPONSIVE TO THE PRESSURE IN SAID INLETCAVITY FOR MOVING SAID VALVE TO ITS OPEN POSITION INDEPENDENTLY OF SAIDELEMENT, RESILIENT MEANS URGING SAID EXHAUST VALVE AT ALL TIME TOWARDSITS CLOSED POSITION, AND PLUNGER MEANS INCLUDING A LOST MOTIONCONNECTION INTERCONNECTING SAID EXHAUST VALVE AND SAID FLUID PRESSURERESPONSIVE ELEMENT TO RETAIN SAID EXHAUST VALVE OPEN ONLY AFTER MOVEMENTTHEREOF TO ITS OPEN POSITION IN